1. Field of the Invention
The invention relates to closer arm assembly for a door closer that automatically closes a door hinged to a door jamb, the closer being mounted to one of the door and the door jamb and including an output shaft that rotates to load a spring when the door is opened, the loaded spring providing the motive force for closing the door.
2. Description of the Related Art
Automatic door closers are well known, and typically include a housing which can be mounted to one of the door and the jamb, a piston in the housing, a closer spring which acts on the piston, an output shaft which rotates as the piston moves, and hydraulic channels and valves that regulate the closing movement. The rotation of the output shaft is typically translated to linear movement of the piston by a rack and pinion arrangement. An example is disclosed in U.S. Pat. No. 6,618,899.
Closer arm arrangements include both single arm and double arm arrangements. In a single arm arrangement, one end of the arm is connected to the output shaft of the closer, and the other end is connected to a shoe in a slide track. Double arm arrangements include regular arm, top jamb, and parallel arm. In the regular arm arrangement, the closer is typically mounted on the top of the door on the hinge side (pull side), and the connecting arm is attached to the frame face on the hinge side at a right angle to the door. In the top jamb arrangement, the closer is typically mounted to the frame face on the opposite to hinge side (push side), and the connecting arm is attached to the door on the opposite to hinge side at a right angle to the door. In the parallel arm arrangement, the closer is typically mounted on the top of the door on the opposite to hinge side (push side), and the connecting arm is attached to the door frame so that it is substantially parallel to both the main arm and the door when the door is closed. The arms pivot relative to each other like scissors as the door opens, their relative angle roughly following the angle of the door relative to the frame.
Parallel arm arrangements may include a soffit plate mounted to the soffit of the door frame, and the soffit plate may include a stop in the form of a spring loaded bumper which limits travel of the connecting arm. Known bumpers do not have any cushioning at the contact point with the connecting arm, which results in an undesirable banging noise when the connecting arm hits the bumper. In an arrangement sold by Sargent, the connecting arm contacts a piston which is loaded by a spring in a housing which is only secured by a single bolt. This permits the housing to pivot, but provides only limited resistance to shear stress. U.S. Pat. No. 5,517,720 discloses a bumper having a housing which holds a spring fixed to the soffit plate by a tension pin so that the housing itself makes resilient contact with the connecting arm. Here the tension pin is subject to failure by repeated tensile stress.
Parallel arm arrangements may also include a stop mounted on the end of the main arm, the first end of the connecting arm being pivotably connected to the main arm adjacent to the second end. Here too an undesirable banging occurs when the connecting arm hits the stop.
Door closer arm arrangements may also include a hold open device which maintains the door in an open position with sufficient holding force to resist automatic closing. When the hold open device is engaged, the door may be closed by applying extra force to overcome a spring force in the hold open device. When the device is disengaged (released), the door will close automatically under the force of the spring in the closer.
Known hold open devices typically include a spring-loaded detent in the form of a pin or ball which cooperates with a recess, and is effective between the connecting arm and the soffit plate, or between the two arms at the elbow. A known parallel arm arrangement, sold by Norton Door Controls under the trade name Unitrol, has a fixed pin stop on the main arm and utilizes a holding device including a holding plate having a recess on the main arm, and a housing with a detent loaded by a leaf spring on the connecting arm. The leaf spring is in compression in the engaged position, and requires further compression to release the detent from the socket. Release is achieved by turning a screw a quarter turn against the increasing compression of the leaf spring, which requires using a screw driver.